Where's the Seraph Vendor in the Badass Crater of Badassitude? Map screenshots and a general description of how to get there would be stellar.
Taken from the Gearbox forums:
In the first area Mr. Torgue sends you before you meet Piston, right on the way to the arena door. There's ammo/med vendors, the Seraph door is nearby. Check the map for another $ icon.